A fuel metering system includes a bypass valve configured to receive a fuel flow under a pressure P1, a pressure regulating valve in fluid communication with the bypass valve and configured to receive a fuel flow under a pressure PQ, a metering valve in fluid communication with the bypass valve and the pressure regulating valve, and configured to receive the fuel flow under the pressure P1 and to output a fuel flow under a pressure P2, a single stage servo valve in fluid communication with the bypass valve, the pressure regulating valve and the metering valve, and configured to receive the fuel flow under the pressure P1, and to output the fuel flow under the pressure PQ, and to output a fuel flow under a pressure PM, and a linear variable differential transformer coupled to the metering valve.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A fuel metering system, comprising: a bypass valve (BV) configured to receive a fuel flow under an incoming fuel pressure and to output a fuel flow under a drain pressure while regulating a servo system delta pressure, the servo system delta pressure being a difference between the incoming fuel pressure and a cavity pressure; a pressure regulating valve (PRV) in fluid communication with the BV and configured to receive a fuel flow under an intermediate pressure and to output a fuel flow under the drain pressure while regulating a metering window delta pressure, the metering window delta pressure being a difference between the incoming fuel pressure and an outgoing fuel pressure; a metering valve (MV) in fluid communication with the BV and the PRV, and configured to receive the fuel flow under the incoming fuel pressure and to output a fuel flow under the outgoing fuel pressure; a single stage servo valve (SSSV) in fluid communication with the BV, the PRV and the MV, and configured to receive the fuel flow under the incoming fuel pressure, and to output the fuel flow under the intermediate pressure, and to output a fuel flow under a modulated pressure; and a linear variable differential transformer (LVDT) coupled to the MV.
2. The system as claimed in claim 1 wherein the BV includes a first cavity configured to receive the fuel flow under the intermediate pressure and a second cavity configured to receive a fuel flow under the incoming fuel pressure.
3. The system as claimed in claim 2 wherein the PRV includes a first cavity configured to receive the fuel flow under the outgoing fuel pressure and a second cavity configured to receive a fuel flow under the incoming fuel pressure.
4. The system as claimed in claim 3 wherein the BV and the PRV regulate a pressure difference between the incoming fuel pressure and the outgoing fuel pressure and contribute to a bypass fuel flow under the drain pressure.
5. The system as claimed in claim 1 wherein the BV includes an annular cavity configured to receive the fuel flow under the incoming fuel pressure.
6. The system as claimed in claim 5 wherein the PRV includes an annular cavity configured to receive the fuel flow under the intermediate pressure.
7. The system as claimed in claim 6 wherein the BV and the PRV contribute to a bypass fuel flow under the drain pressure from the annular cavity in the BV and the annular cavity in the PRV.
8. The system as claimed in claim 1 wherein the MV includes a first cavity configured to receive the fuel flow under the intermediate pressure and a second cavity configured to receive the fuel flow under the modulated pressure.
9. The system as claimed in claim 8 wherein the MV includes an annular cavity configured to receive the fuel flow under the incoming fuel pressure and to output the fuel flow under the outgoing fuel pressure.
10. The system as claimed in claim 9 wherein the BV and the PRV regulate a pressure difference between the incoming fuel pressure and the outgoing fuel pressure and contribute to a bypass fuel flow under the drain pressure.
11. The system as claimed in claim 1 wherein the PRV is configured to set the incoming fuel pressure to a value over the outgoing fuel pressure, and to regulate the intermediate pressure.
12. The system as claimed in claim 11 wherein the BV is configured to set the cavity pressure to a value below the incoming fuel pressure.
13. A fuel metering system, comprising: a bypass valve (BV) configured to receive a fuel flow under an incoming fuel pressure; a pressure regulating valve (PRV) in fluid communication with the BV; a metering valve (MV) in fluid communication with the BV and the PRV, and configured to output a fuel flow under an outgoing fuel pressure; a single stage servo valve (SSSV) in fluid communication with the BV, the PRV and the MV; and a linear variable differential transformer (LVDT) coupled to the SSSV and to the MV, wherein the BV and the PRV regulate a pressure difference between the incoming fuel pressure and the outgoing fuel pressure and contribute to a bypass fuel flow under a drain pressure.
14. The system as claimed in claim 13 wherein the BV includes a first cavity configured to receive a fuel flow under an intermediate pressure and a second cavity configured to receive a fuel flow under the incoming fuel pressure.
15. The system as claimed in claim 14 wherein the PRV includes a first cavity configured to receive the fuel flow under the outgoing fuel pressure and a second cavity configured to receive a fuel flow under the incoming fuel pressure.
16. The system as claimed in claim 13 wherein the BV includes an annular cavity configured to receive the fuel flow under the incoming fuel pressure.
17. The system as claimed in claim 16 wherein the PRV includes an annular cavity configured to receive a fuel flow under an intermediate pressure.
18. The system as claimed in claim 13 wherein the MV includes a first cavity configured to receive a fuel flow under an intermediate pressure and a second cavity configured to receive a fuel flow under a modulated pressure.
19. The system as claimed in claim 18 wherein the MV includes an annular cavity configured to receive the fuel flow under the incoming fuel pressure and to output the fuel flow under the outgoing fuel pressure.
20. The system as claimed in claim 13 wherein the PRV is configured to set the incoming pressure to a value over the outgoing fuel pressure, and to regulate an intermediate pressure, and wherein the BV is configured to set the intermediate pressure to a value below the incoming fuel pressure.
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April 24, 2012
December 30, 2014
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